Macromolecular organic photoconductors themselves possess film forming ability. Accordingly, it is not necessary to use a film forming binder in combination with macromolecular organic photoconductors when forming an electrophotographic photoreceptive layer (electrophotographic photoreceptive film). The macromolecular organic photoconductor can be used to form the photoreceptive layer by itself. However, films of poly-N-vinylcarbazole and other macromolecular organic photoconductors, including polyvinyl triphenylpyrazoline, polyacenaphthylene and the like, are very fragile.
When using a macromolecular organic photoconductor as an electrophotographic photoreceptive layer, the photoconductor is generally dissolved in an appropriate solvent and coated on a support. Under such a circumstance, when using fibrous porous material, like paper, as a support, the macromolecular organic photoconductor can permeate into the support. Because of the permeation into and bonding with the paper, such material is useful despite its own inflexible property. However, when the macromolecular organic photoconductor is laminated on a smooth support surface, like a metal plate or a plastic film, there occurs a disadvantageous phenomenon in that the electrophotographic photoreceptive layer is distorted by shrinkage accompanying the evaporation of the solvent therefrom. Accordingly, it is cleaved from or delaminated from the support.
In addition, a film of a macromolecular organic photoconductor is generally brittle. Consequently, when it is processed into an electrophotographic film or sheet, the electrophotographic photoreceptive layer will often break along cut planes when the film or sheet is cut or slit in order to form the finished goods. Furthermore, crevices may generated by bending the film or sheet during handling or when it is conveyed in the form of roll film. Accordingly, it cannot be submitted to practical use if it is left as it is.
An attempt has been made to eliminate the inherent brittleness of such macromolecular organic photoconductors by copolymerization with monomers having an intramolecular plasticizing effect (Japanese patent publication Nos. 24753/68, 43955/71 and 18780/75). However, if the fraction of such monomers is increased till sufficient plasticizing effect is attained, electrophotographic characteristics are deteriorated and the original functions as the photoconductor are lost. In accordance with another known method of softening macromolecular organic photoconductors, certain substances are included as additives. These and other techniques are disclosed in, e.g., Japanese patent publication Nos. 14527/75, 18780/75 and 5943/76; Japanese patent application (OPI) Nos. 19442/75, 115039/75 and 115536/75 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"); and so on. However, these techniques cause deterioration of electrophotographic characteristics if they are utilized to the extent that sufficient flexibility is aquired. More specifically, when utilizing these techniques, obtaining good flexibility is incompatible with obtaining desirable electrophotographic characteristics.